unclutter is a program which runs permanently in the background of an X11
session.  It checks on the X11 pointer (cursor) position every few seconds, and
when it finds it has not moved (and no buttons are pressed on the mouse, and
the cursor is not in the root window) it creates a small sub-window as a child
of the window the cursor is in.  The new window installs a cursor of size 1x1
but a mask of all 0, ie an invisible cursor.  This allows you to see all the
text in an xterm or xedit, for example.  The human factors crowd would agree it
should make things less distracting.

Once created, the program waits for the pointer to leave the window and then
destroys it, restoring the original situation.  Button events are passed
transparently through to the parent window.  They will usually cause the cursor
to reappear because an active grab will be made by the program while the button
is down, so the pointer will apparently leave the window, even though its x-y
position doesn't change.
